Meningioma
Meningiomas are a form of primary brain tumor that develops from the meninges, which are three main layers of tissue that cover the brain and spinal cord. These tumors usually grow inward, putting pressure on the brain or spinal cord, but they can also grow outward, thickening the skull. The majority of meningiomas are slow-growing and usually benign. Cysts, calcifications (calcium aggregates), and closely packed groups of blood vessels are found in some of these. There are numerous systems for naming and categorizing these tumors. Meningiomas are classified according to the type of cells that make up the tumor in one system. The most frequent type of meningioma is syncytial (or meningothelial), which has exceptionally plump cells.
Fibroblastic meningiomas are characterized by long, thin cells. Both types of cells can be found in transitional meningiomas. To characterize the overall grade of meningiomas, another method employs the labels benign, atypical, and malignant. Benign meningiomas in this system have easily identifiable, well-differentiated (normal-looking) cell types that grow slowly. Atypical tumors account for 9–15% of all meningiomas. They comprise proliferating cells that are more likely to grow back following therapy, even if excision appears to be complete. As a result, these tumors must be closely monitored for signs of recurrence. Malignant tumors, often known as "anaplastic" tumors, are poorly differentiated variants that recur frequently. Malignant meningiomas are extremely aggressive and hard to treat, despite their rarity. Another popular practice is to include the tumors' origin in its name. A parasagittal meningioma, for example, is found near the sagittal venous sinus, a large blood vessel that runs through the apex of the cerebral hemispheres. Sphenoid ridge meningioma is a kind of meningioma that develops along the bone ridge behind the eyes and nose. Despite their benign character, some meningiomas can cause problems since they are difficult to eliminate when they are situated in functionally sensitive or difficult-to-reach locations. Stereotactic radiation or radiosurgery, based on the circumstances, maybe particularly beneficial in certain of these cases.
Epidemiology
In 2015, the global incidence of primary brain tumors was projected to be 10.80 per 100,000 people. Between 2010 and 2014, the frequency was 8.2 per 100,000 people, indicating that it has been rising. The average age of the presenter is 67, with a female to male ratio of approximately 2.4:1. African Americans have a greater incidence, with a female to male ratio of 2.3 to 1. Meningiomas represented 37% of all primary central nervous system tumors and 50 percent of all benign primary central nervous system tumors, according to histopathological confirmation. It affects between 1.9 and 14 people per 100,000 every year. In the United States, the prevalence is 97.6 per 100,000 people, with more than 170,000 people are diagnosed with a meningioma.
Adults are more likely than children to develop meningioma, with a rate of 37.7 per 100,000 in the 74 to 84 age group. In children aged 1 to 19, the rate is 0.15 per 100,000. Meningiomas are linked to neurofibromatosis type 2 in about 1 percent of cases. According to the WHO, about 80 percent of meningiomas are classified as normal or grade 1. Atypical or grade 2 meningiomas account for 18% of them, whereas anaplastic or grade 3 meningiomas account for 1.8 percent. Meningioma recurrence can be as high as 20% after ten years. Higher-grade meningiomas have been linked to a high rate of recurrence. The recurrence rate in grade 3 ranges from 50 to 95 percent. The recurrence rate in grades 1 and 2 is 6 to 26 percent and 30 to 53 percent, respectively. In patients aged 20 and older, spinal meningiomas represent 30 to 38% of all primary intradural spinal tumors in the United States, with an age-adjusted frequency of 0.19 per 100,000 of the population. Females have an 80 percent chance of developing these meningiomas.
Meningioma Etiology
The majority of meningiomas are sporadic, however, some have been linked to specific disorders and risk factors. Obesity, alcohol consumption, irradiation, radiotherapy, hormonal factors such as exogenous hormone intake, hormone replacement therapy, oral contraceptive pill use, and breast cancer can all raise the risk of meningiomas.
Progesterone, estrogen, and androgen receptors are found on the membranes of meningiomas. In up to 73 percent of cancers, progesterone receptors can be detected. They change size throughout pregnancy and the luteal phase of the menstrual period. Because of the hormonal aspect, females have a higher prevalence. Meningioma-affected first-degree relatives, as well as hereditary diseases such as neurofibromatosis type 2, von Hippel Lindau disease, multiple endocrine neoplasia type 1 (MEN1), and Cowden disease, are all linked to a higher frequency.
Pathophysiology
Meningioma is a type of cancer that arises from the cells of the meningothelial arachnoid cap. The majority of meningiomas are sporadic, benign, and grow slowly. Malignant meningiomas, on the other hand, frequently contain several chromosomal alterations and usually have one or more focal chromosomal deletions. More genetic alterations are linked to faster tumor growth and a higher tumor grade.
One of the most frequent contributing factors in sporadic meningiomas is a genetic mutation on chromosome 22 in neurofibromatosis type 2. 14q and 18q chromosomal mutations have also been documented in meningiomas. CREB binding protein, phosphatase and tensin homolog, cyclin-dependent kinase inhibitor 2A, and neurofibromatosis 1 are other genes present in hereditary meningiomas.
Meningioma Symptoms
The symptoms of intracranial meningioma vary depending on which part of the brain is involved. Supratentorial meningiomas account for the majority of intracranial meningiomas. The parasagittal, brain convexity, sphenoid ridge, anterior and posterior parafalcine areas, and olfactory groove are all prevalent locations. Suprasellar, posterior fossa, intraventricular, and intraorbital regions have all been documented as sites for intracranial meningiomas.
Hypertonia, hyperreflexia, positive Babinski signs, paresis, or paralysis are common upper motor neuron findings in intracranial meningioma. loss of smell, headaches, drowsiness, impaired vision, convulsions, papilledema, and behavioral abnormalities are among the other symptoms mentioned. Paresis or paralysis of the afflicted contralateral limb can occur in patients with parasagittal and brain convexity meningiomas.
Sphenoid ridge meningiomas that affect the supraorbital fissure or the cavernous sinus can cause cranial nerve palsies and convulsions in patients. Foster-Kennedy syndrome can be caused by olfactory groove meningiomas. loss of smell, contralateral papilledema, and ipsilateral optic nerve degeneration are all symptoms of this illness.
The optic, trochlear, trigeminal, and abducens nerves can all be affected by cavernous sinus meningioma. Suprasellar meningiomas can cause mental, cognitive, and behavioral problems in patients. Bulbar palsy, cerebellar symptoms, paresis, facial nerve palsy, hearing loss, lower cranial nerve palsies, and neck pain are all signs of posterior fossa and foramen magnum meningiomas. Obstructive hydrocephalus is often caused by intraventricular meningioma. Meningiomas of the parasellar, cavernous sinus, and orbits can cause visual loss and proptosis. Pain and radiculopathy are the most prevalent symptoms of spinal meningiomas, followed by neurological impairments. Depending on the position and entrapment of the nerve roots, the neurological impairments could be upper or lower motor neuron symptoms. Fatigue, hypotonia, muscle fasciculations, and hyporeflexia are all indications of lower motor neuron disease. During a medical assessment, localized spinal pain is sometimes discovered.
Meningioma Diagnosis
The diagnosis of meningioma is made based on the patient's medical history, physical exam, and radiological tests. A head contrast-enhanced Computed tomography can be used to detect hyperostosis or calcified meningiomas in patients who are not candidates for a Magnetic resonance. Meningiomas frequently present as hyperdense or isodense dura-based lesions on non-contrast head CT scans. Most meningiomas appear as homogeneous dense increased dura-based lesions with or without cerebral edema on a contrast-enhanced head Computed tomography. Head Computed tomography is superior in detecting tumor calcifications and hyperostosis, as shown in cases of ossified meningiomas and meningioma en plaque.
Brain Magnetic Resonance Imaging (MRI)
Brain MRI with contrast is the best radiological approach for diagnosing meningioma. Extra-axial lesions exhibit a homogeneous enhancement with a characteristic called the dura tail, which can assist identify them from intra-axial lesions. An MRI of the brain can also be used to assess venous sinus involvement. The use of a brain MRI can also aid in the detection of cystic lesions in meningiomas, which may have a mushroom-like shape. The tumor invagination in the brain parenchyma is explained by this symptom. Meningiomas are hypointense on T1-weighted images and hyperintense on T2-weighted images on brain MRI without contrast. On non-contrast brain MRI, some meningiomas may look as isointense on T1 and T2 weighted images. The CSF vascular cleft is another signal to look for. The cleft, which occurs when the CSF or cerebral cortical vessels become entrapped between the meningioma and the underlying cortex, is utilized to identify an extra-axial meningioma from an intra-axial lesion.
There may be calcifications and peritumoral cerebral edema, which is usually of the vasogenic kind. The breakdown of the blood-brain barrier is the most common cause of cerebral edema. It induces vasogenic edema by causing extracerebral protein-rich fluid to pool in the cerebral parenchyma. Edema is shown as hyperintensity in T2 weighted images on brain MRI. Peritumoral edemas' exact causes have yet to be determined in the literature. However, some characteristics or predictors can impact the development of peritumoral edema. On brain MRI, these include the disappearance of an arachnoid plane, elevated Ki-67 antigen labeling index values, and uneven tumor borders. Other reasons include tumor cells releasing vascular endothelial growth factor, which eventually affects the tumor-brain barrier, resulting in edema.
One of the useful markers for distinguishing an extra-axial lesion from an intra-axial lesion is the white matter buckling sign. The inward pressure or buckling of the white matter, as well as the persistence of the grey-white junction even in the presence of edema, can be seen on a head Computed tomography or a brain MRI. Extracerebral fluid collection in extra-axial lesions such as meningioma is frequently related to white matter buckling.
MRI Spectroscopy
To identify malignant meningiomas, MRI spectroscopy can be employed. It evaluates the metabolic and chemical components of healthy neural tissue to the metabolic and chemical components of the malignant tumor. MRI spectroscopy analyzes various metabolites to determine the metabolic characteristics associated with the tumor. Choline levels are higher in some meningiomas, but creatinine is reduced.
Digital Subtraction Angiography
Digital subtraction angiography is a technique for demonstrating meningiomas' nutritional arteries and distinguishing between pial and dural blood flow. Parasagittal meningiomas are more likely to have Sinus pericranii. It's a vascular abnormality in which the intracranial dural sinuses and extracranial veins don't connect properly. Hypervascular meningiomas can also have sunburst characteristics, CSF-vascular clefts, and the mother-in-law sign. The meningioma in the mother-in-law sign has shown some arterial enhancement and remains highly opacified during the venous phase. In individuals with big meningiomas, digital subtraction angiography is beneficial during surgery. During digital subtraction angiography, preoperative embolization of the tumor feeders can help with surgical removal by reducing intraoperative hemorrhage and softening the tumor.
Another radiographic approach for surgical preparation and postoperative monitoring is a positron emission tomography scan. It can aid in the delineation and definition of the vasculature as well as the tumor-brain junction.
Meningioma Treatment
Meningioma Surgical Treatment
Although some tumors are incurable, resection is the standard therapy for meningiomas that are found in an accessible location of the brain or spinal cord. Another consideration for brain surgeons is whether or not the important organs (heart, lungs, kidneys, and liver) are capable of withstanding anesthesia and operation. The purpose of surgery is to get tumor tissue for diagnostic purposes and to excise as much tumor as practicable. A biopsy to collect a specimen of tumor tissue may be done if the tumor cannot be excised. A three-dimensional, or stereotactic, map of the brain can be created using computer software that combines multiple MRI images collected before operation. This diagram aids the neurosurgeon in planning the surgery to excise as much of the tumor as feasible while preserving important brain functions.
The doctor may employ stereotactic scanning and instrument guiding technology to traverse through the brain during the procedure. Occasionally, surgery is performed in the context of a special MRI (intraoperative MRI), which enables the surgeon to observe the tumor during the procedure and identify the scope of the tumor removal. High-powered microscopes may be utilized to aid the surgeon in seeing the tumor more clearly. To break apart and suction out pieces of the tumor, ultrasonic aspirators are used. When a tumor cannot be totally removed, partial removal can assist to alleviate symptoms. The residual tumor could subsequently be treated with radiation.
Radiation Therapy
Inoperable cancers, tumors that are not entirely eliminated during surgery, atypical and aggressive tumors, and recurrent tumors may all benefit from external beam radiotherapy. There are several types of radiation, each with varying doses and timings. The majority of radiation treatments, on the other hand, are directed at the tumor and a limited section around it. External beam radiotherapy delivered five days a week for five or six weeks is known as conventional external beam radiation.
Stereotactic radiotherapy targets the tumor with converged beams of radiation. Radiation beams are conformed to the contour of the tumor in intensity-regulated radiotherapy. Stereotactic radiosurgery employs a series of tightly focused radiation beams to precisely deliver a single high-dose therapy to the tumor while reducing the effects on surrounding normal tissue. As a result, despite the name, this is a noninvasive process with no actual surgery. This could be especially beneficial for individuals who aren't good surgical candidates, have tumors in high-risk areas of the brain, or have recurrences that aren't responding to traditional surgical and radiation treatments.
The downsides are that no tissue is collected for investigation under the microscope if no surgery or biopsy is performed; the method may only impede further growth, stabilizing, rather than killing or removing, the tumor; and the technology is limited to comparatively small tumors, usually, those that are not cancerous and less than three millimeters. Large tumors or lesions adjacent to essential structures are frequently treated with conventional or stereotactic radiation. While stereotactic radiosurgery uses a single massive dose of focused radiation, stereotactic radiotherapy uses lower doses of focused radiation spread out over a prolonged period of time. This lessens the risk of swelling or damage to nearby structures.
Other Treatment
Systemic therapy may be recommended for lesions that are not surgically approachable or for patients who are unable to receive further radiotherapy. Some of these treatments are available through clinical trials, which are organized research studies. The doctor can tell you if you're a good candidate for one of these studies.
Several different therapy options have been or are being investigated:
- Hydroxyurea is a urea derivative (used as a radio-sensitizing medication in the management of other types of tumors)
- Inhibitors of the progesterone receptor
- Somatostatin-related compounds (hormones that stop growth hormones from being released)
- Molecular agents with a specific target
- Inhibitors of platelet-derived growth factor receptor
- Inhibitors of vascular endothelial growth factors
- Immunotherapy, which involves the use of biological agents to boost the immune response
A variety of medications are also used to manage the symptoms of meningioma. Corticosteroids are used to reduce edema around the tumor. Anticonvulsant medications keep seizures under control. Antiemetic medications help to prevent vomiting and manage nausea.
Watchful Waiting
Some meningiomas may be closely monitored based on the tumors' position, symptoms induced by the tumor, and sometimes patient preference. Scans will be advised during the observation period, and those scans must be completed. If the doctor recommends a period of observation, keep in mind that any new or changing symptoms should be mentioned to the doctor as soon as possible.
Meningioma Recurrence
The majority of meningiomas are benign and can be surgically removed. However, when all of the tumor cells cannot be excised with surgery or eliminated with other therapies, brain tumors reappear. These cells replicate over time, resulting in tumor recurrence. The doctor can discuss the likelihood of a recurrence of the tumor with you. In general, roughly 5 percent of totally resected benign meningiomas, 30 percent of partially removed benign meningiomas, and 40 percent of atypical meningiomas have recurred five years after surgery. It's also potential that the meningioma will reappear as a more aggressive or higher-grade tumor, however, this is uncommon. If the tumor recurs, further surgery and potentially radiation treatment may be recommended, based on the general health and the tumors' growth patterns.
Following a history of conventional radiotherapy, focused kinds of radiotherapy, such as stereotactic radiotherapy or radiosurgery, may be resumed or employed. Clinical trial therapies may potentially be utilized to treat recurring lesions.
Recovery after Treatment
The length of recovery time varies, as it does with any brain tumor therapy. The recovery period is affected by the patient's age and general health, the tumors' position and size, and the type of treatment. Inquire with the doctor about possible side effects before surgery. Depending on the location of the tumor, muscle synchronization or speech impairments may emerge after surgery; however, these issues are usually only transitory. Many brain tumor patients learn about the benefits of rehabilitation therapy during this time of recovery. Rehabilitative therapy aims to help people regain their physical, occupational, and psychological abilities. Physical, occupational, and speech therapy may be provided to assist alleviate some of the symptoms that may follow a tumor or treatment.
A memory training procedure called cognitive retraining is used to train another section of the brain to take over the responsibilities of the damaged part. Tumors near the optic nerves may necessitate the use of visual aids. Just as crucial are support services that assist patients and family members in coping with a brain tumor diagnosis.
Meningioma Prognosis
When a person is diagnosed with meningioma, they generally have a lot of concerns about their prognosis. They may want to know about the dangers of their surgery if they'll require follow-up care or further therapies, whether or not the tumor will influence their life, and how likely it is that their tumor will return. Although the term prognosis is likely related to cancerous tumors, a prediction of outcome may be more appropriate for someone who has a meningioma. We recommend that you ask the doctor for these follow-up inquiries. They'll be able to reply to your worries based on the specifics of the tumor. The doctor can also describe the treatment plan, including the benefits and hazards of the treatment plan he or she has recommended for you, as well as what to expect in the future.
Conclusion
Despite the fact that meningiomas are benign tumors, they have a substantial effect on patients and can be a problem to physicians in terms of ongoing surveillance and care. When gross total resection is possible, surgical removal remains the gold standard. Adjuvant therapy is essential in cases when maximal excision cannot be achieved safely, inoperable cases, residual tumor persists, and the tumor is an aggressive high-grade tumor. As previously stated, many of these adjuvant treatments have downsides, and few systemic medications have been licensed or proven to be effective. To overcome these therapeutic gaps, more research and clinical trials will be required.